PROJECT SUMMARY/ABSTRACT One in five transgender women (TGW) in the U.S. is infected with HIV. The burden is particularly onerous for African Americans. While 16% of U.S. TGW are Black, over half of all new cases in TGW from 2009-2014 were among African Americans. Further, African American TGW experience a complex interaction of racism, sexism, and transphobia that leads to health disparities across the entire spectrum of HIV-related outcomes. Despite the clear need for effective HIV resources for African American TGW, no CDC-defined evidence- based interventions (EBIs) exist for this group. We intend to meet this need with Shine, a culturally-tailored, theoretically-driven mobile intervention for Black TGW. The Information-Motivation-Behavioral Skills (IMB) model will guide the development of behavior change messages tailored to a user?s HIV status. Beyond information, motivation, and skills, a unique socio-cultural context also influences TGW?s ability to perform HIV-related behaviors. To account for this, we will contextualize the IMB-based HIV content by addressing a key intrapsychic need among Black TGW: gender affirmation. According to the Model of Gender Affirmation, a need for gender identity validation often leads TGW to engage in behaviors that are counter to HIV prevention and treatment goals. To further improve HIV outcomes, Shine will reduce barriers to HIV behaviors caused by gender affirmation needs and empower Black TGW to affirm their gender in healthier ways. Shine will be the first mobile intervention for African American TGW that is theory-based, individually- tailored, and empowering. All users will receive HIV-related informational, motivational, and skill-building text messages. Additional messaging will provide strategies for gaining gender affirmation. These text messages will be supplemented by three types of web-based videos: scripted vignettes, unscripted peer narratives, and educational instruction. Links to these videos will be integrated into the messaging and will enhance the trans- specific understanding of gender affirmation within our IMB framework. An innovative theory-based HIV behavioral intervention designed to overcome the unique barriers facing African American TGW; that addresses elements across the entire HIV care continuum; that is delivered in a way that empowers, educates, and engages a stigmatized population; and that relies on a technology that is part of the everyday lives of target end-users has the significant potential to meaningfully reduce HIV disparities. The results of Phase I strongly support the feasibility and potential effectiveness of the program ? far exceeding the usability benchmarks established in the Phase I proposal. In Phase II, we will complete development of Shine and test its effectiveness in a randomized controlled trial with 215 African American TGW. Participants will be randomly assigned to receive either Shine or mobile HIV education materials. Before and 6 months after random assignment participants? composite risk for HIV transmission, HIV preventive and treatment behaviors, barriers to those behaviors, and gender affirmation needs will be assessed.